In the official Blizzard scenario map for Warcraft III, called Blizzard's Tower Defense, the prison was guarded by three wardens. The prisoners broke out of their cells but were stopped by the wardens.

Prisoners are kept inside individual cells.

The most hardened criminals in the universe are held here, in a jail devised by those that would rather never see such vile creatures set free. Now these corrupted specimens of humanity, who yearn for freedom and for revenge on their captors, have come up with a plan to escape. With hope nearly lost, three prison wardens will carry out a plan of their own to stop these treacherous prisoners and protect the civilized world.

Thinking back on it, you have to wonder; was it really a good idea to put all the worst criminals in the same jail?